Breakthrough: Researchers discover 27 genes that could halt cancer

Human cells normally contain two copies of tumour suppressor genes, which work to prevent tumour formation by slowing down cell division and growth. When these genes are deleted, through genetic mutations, for example - this gives rise to cancer development

Human cells normally contain two copies of tumour suppressor genes, which work to prevent tumour formation by slowing down cell division and growth. When these genes are deleted — through genetic mutations, for example — this gives rise to cancer development.

As a general rule, in order for tumours to form, both copies of the tumour suppressor genes must be malfunctioning in a cell. This is because a single functioning tumour suppressor gene can still produce the proteins needed to decelerate cell division and growth.

But the researchers note that identifying these double-gene abnormalities is challenging. One problem is that tumours often contain a mix of healthy and cancerous cells in varying proportions, making it difficult to determine whether one or two tumour suppressor genes are missing in cancer cells.

They have created a statistical model — which utilises single nucleotide polymorphism analysis — that could help to overcome such problems. So far, it has helped them to identify an array of new tumour suppressor genes.

The researchers used their model to assess the number of tumour suppressor genes in the cells of 2,218 tumours across 12 types of cancer. These included breast, lung, colorectal, ovarian, and brain cancers.

The model not only enabled the team to calculate the relative proportions of healthy and cancerous cells in each tumour, making it easier to determine the presence of tumour suppressor genes in the cells, but it also revealed the distinct “DNA footprint” of tumour suppressor genes. This allowed them to distinguish these genes from non-harmful gene mutations.

As a result, the researchers identified a total of 96 gene deletions among the tumours. These included 43 tumour suppressor genes, of which 27 were previously unknown.

“Our study demonstrates,” explains senior study author Peter Van Loo, also of the Francis Crick Institute, “that rare tumour suppressor genes can be identified through large-scale analysis of the number of copies of genes in cancer samples.”

“Cancer genomics is a growing area of research, and the computational tools we use are a powerful way to find new genes involved in cancer,” he adds.

Findings may fuel personalised treatments

Cancer remains one of the biggest health burdens worldwide. There were around 14.1 million new cases of cancer diagnosed across the globe in 2012, with lung cancer, breast cancer, and colorectal cancer among the most common.

In the United States, more than 1.6 million new cancer cases were diagnosed last year, and more than 595,000 people died from the disease.

According to Demeulemeester and his colleagues, their findings may lead to personalised cancer therapies — that is, treatments that are tailored to individual patients based on the genetic makeup of their tumours.

“Using this powerful toolkit, we’ve uncovered rare tumour suppressor genes that when lost in mutated cells, cause cancer. This could pave the way for the development of personalised cancer treatments.”